Solid ink or phase change ink printers conventionally receive ink in a solid form, either as pellets or as ink sticks. The solid ink pellets or ink sticks are typically inserted through an insertion opening of an ink loader for the printer, and the ink sticks are pushed or slid along the feed channel by a feed mechanism and/or gravity toward a heater plate in the heater assembly. The heater plate melts the solid ink impinging on the plate into a liquid that is delivered to a print head for jetting onto a recording medium.
The correct loading and feeding of ink sticks has typically been accomplished by incorporating loading features, such as, for example, keying, guiding, alignment, orientation and/or sensor actuating features, into the exterior surface of an ink stick. These features are protuberances or indentations that are located in different positions on an ink stick. Corresponding keys or guide elements on the perimeters of the openings through which the ink sticks are inserted or fed exclude ink sticks which do not have the appropriate perimeter key elements while ensuring that the ink stick is properly aligned and oriented in the feed channel. Another method that has been implemented to aid in the correctly loading of an ink stick is the incorporation of encoding features into the exterior surface of ink sticks that interact with sensors in the ink delivery system. Ink stick data may be encoded into these features by configuring the features to interact with one or more sensors in an ink loader to generate a signal or coded pattern of signals that corresponds to information specific to the ink stick. The ink stick data encoded onto the ink stick may be read by the print controller in a suitably equipped phase change ink jet printing device to control imaging operations. For example, the controller may enable or disable operations, optimize operations or influence or set operation parameters based on the ink stick data encoded onto the ink stick.
Customers, however, may not be familiar with the loading features of the various ink stick configurations. Consequently, customers may not know the appropriate orientation for inserting an ink stick into an ink loader. A customer believing that they have correctly oriented an ink stick for insertion may override resistance caused by insertion keying features and inadvertently force an incorrectly oriented ink stick through an opening into a feed channel. If the loaded ink stick is the wrong color for a particular feed channel or if the ink stick is incompatible with the phase change ink jet printer in which it is being used, considerable errors and malfunctions may occur. Even if an ink stick is the correct configuration for use in a particular feed channel, an ink stick that is not oriented correctly prior to insertion may not feed properly along the feed channel and/or may not engage the ink melter appropriately. In addition, encoding features on an ink stick that has been inserted incorrectly may not be positioned optimally in the feed channel to interact with sensors resulting in faulty actuation of the sensors or no actuation at all. Nesting features have been incorporated in ink sticks to benefit feed control, differentiate between models and other benefits but such features have never been configured to serve as obvious orientation aids.